Bigger worlds on 32 bit hardware

In the last release of the unstable branch, a world size (called 'ram killer') was added without an announcement. This size is 80*80 chunks, or (at a default depth of 64) 104 million voxels. It's not actually possible to load that size world in the unstable branch because the memory needs of the geometry buffers used for rendering exceeds the limits of a 32 bit process. Well, that's no longer the case, and these worlds will be available in the unstable branch soon - and are expected to make it into the next official release. A bit of work we couldn't get done for the official release has finally paid off and now we can discard geometry for chunks not in view as needed, bringing the memory usage in the shot below back under 1 GB.

We've also been experimenting with fog of war, and the possibility of not revealing the surface. This works quite well and has for a while, but was left out so far because it doesn't play well with slicing as you can see below. Also, it's a bit odd for a full 3d camera. Does this even make sense when, presumably, dwarves could see what's a fair distance away?